perf: Reduce some clustering computation

src/pointFeature.js

@@ -56,7 +56,9 @@ var feature = require('./feature');
  * @typedef {object} geo.pointFeature.clusteringSpec
  * @property {number} [radius=10] This is size in pixels that determines how
  *   close points need to be to each other to be clustered.
- * @property {number} [maxZoom=18] Never cluster above this zoom level.
+ * @property {number} [maxZoom=18] Never cluster above this zoom level.  For a
+ *   point feature associated with a layer and a map, this will default to the
+ *   map's zoomRange().max value.
  */
 
 /**
@@ -138,6 +140,10 @@ var pointFeature = function (arg) {
 
     // set clustering options to default if an options argument wasn't supplied
     var opts = m_clustering === true ? {radius: 10} : m_clustering;
+    if (!opts.maxZoom && this.layer() && this.layer().map()) {
+      opts = Object.assign({}, opts);
+      opts.maxZoom = this.layer().map().zoomRange().max;
+    }
 
     // generate the cluster tree from the raw data
     var position = m_this.position();

src/util/clustering.js

@@ -3,8 +3,6 @@
  * hierarchically given an array of length scales (zoom levels).
  */
 
-var $ = require('jquery');
-
 /**
  * This class manages a group of nearby points that are clustered as a
  * single object for display purposes.  The class constructor is private
@@ -106,10 +104,10 @@ ClusterTree.prototype.each = function (func) {
  * @returns {geo.geoPosition} The 2-d coordinates of the center.
  */
 ClusterTree.prototype.coords = function () {
-  var i, center = {x: 0, y: 0};
   if (this._coord) {
     return this._coord;
   }
+  var i, center = {x: 0, y: 0};
   // first add up the points at the node
   for (i = 0; i < this._points.length; i += 1) {
     center.x += this._points[i].x;
@@ -122,10 +120,11 @@ ClusterTree.prototype.coords = function () {
     center.y += this._clusters[i].coords().y * this._clusters[i].count();
   }
 
-  return {
+  this._coord = {
     x: center.x / this.count(),
     y: center.y / this.count()
   };
+  return this._coord;
 };
 
 /**
@@ -202,9 +201,6 @@ C.prototype.addPoint = function (point) {
         }
       }
 
-      if (!parent) {
-        $.noop();
-      }
       // create a new cluster with these two points
       newCluster = new ClusterTree(this, zoom, [closest, point]);
       this._clusters[zoom].addObject(newCluster, newCluster.coords());